Medical leads are used in conjunction with a medical device that generates stimulation signals to deliver the stimulation signals from the medical device to a target stimulation site within a body of a patient. The medical leads may be implanted through a percutaneous procedure where an introducer needle is inserted into the body, and a medical lead is inserted through a lumen in the needle. A stylet may be included within a lumen of the medical lead to guide the medical lead from the needle to the target site.
One issue when implanting the medical lead is that the needle must be of adequate size to facilitate the introduction of the medical lead. However, a smaller needle is less bothersome to the patient. Thus, minimizing the diameter of the lead is desirable so that the size of the introducer needle may also be minimized.
Another issue that occurs once the medical lead is implanted is that the medical lead needs to have a fixed position at the target site, which is particularly true when assessing the efficacy of therapy during a trial period. Movements by the patient may encourage the medical lead to migrate and therefore a fixation structure may be required to provide the fixation of the lead at the target site. However, the structure for fixation may contribute to the size of the medical lead which may call for an undesirable increase in the size of the introducer needle. Furthermore, explantation of the lead may be more difficult due to the presence of the fixation structure which resists movement in the direction of explantation.
The effectiveness of a fixation structure may also be limited by the compliance of the body of the lead. The body of the lead needs a degree of firmness to support the electrodes and to maintain their alignment when at the target site. Yet a stiff lead body extending toward the proximal end of the lead is counterproductive to the fixation structure.